Should I get a sand, cartridge, or DE filter for my pool?

Stick with a sand filter unless you’re obsessed with clarity. Sand filters are easiest to maintain and good enough for most pools. Cartridge filters are a decent middle ground, but DE filters give the clearest water at 5 microns or less — though they require more work, like adding fresh DE powder after every backwash. For a residential pool, get a sand filter; for a show pool or if you obsess over clarity, go DE.